The contract network of clinical trial sites will evaluate systematically the safety and efficacy of new female contraceptive drugs and devices as well as drug treatments of gynecologic conditions in Phase I, II, and III clinical trials. The study design will be specified in each Request for Task Order Proposals. The results of these clinical trials would be the basis for advancing candidate drugs and devices through development, with the ultimate goal of submission to the FDA in support of a New Drug Application (NDA), Premarket notification 510k, Premarket Approval (PMA) or Investigational Device Exemptions (IDE). Based upon site capabilities, the Principal Investigator (and other site personnel as appropriate) shall participate in the development of protocols in cooperation with personnel from the Statistical and Clinical Coordinating Center and with NICHD program personnel. The candidate protocols, drugs or devices to be evaluated clinically under this contract shall be selected by the NICHD with consultation from the Scientific Advisory Committee of the CCTN. There is a demand for new methods of contraception that can provide effective protection against unintended pregnancy as well as reduce the risk of venous thromboembolism (VTE), particularly for obese women. A new vaginal ring that can deliver a high dose progestin (Nestorone) and a low dose of estradiol (E2) may provide effective and safe contraception for women. The objective of the dose finding study is to identify a dose that can provide reliable contraception and acceptable bleeding patterns for up to 6 months of use.